Navigation and fingerprint sensor

Abstract

A pressure sensitive cursor control suitable for applications that include cellular phones and personal data assistants includes a pressure sensor array suitable to detect a human fingerprint. Cursor control is provided by subtle finger movement. Sequential images of the finger are captured and compared to determine planar movement or data entry. Performance may be improved by sampling zones within the captured image and comparing the zones with those in an earlier image. Performance could also be improved by subsampling the array. While the full resolution of the pressure-sensing array is needed to capture ones fingerprint and execute an authentication function only a subsampled image from the array is needed to derive meaningful navigation data. The pressure sensor array is designed on a glass substrate in order to drive down the unit cost. The silicon companion chip where the data is interpreted also drives the array and can therefore sub-sample the array when navigating and/or get a full resolution image when authenticating.

1. A device comprising:
 a mobile embedded device having a cursor manipulator, the cursor manipulator including,
 a sensing surface operative to sense contact by the human finger, the contact corresponding to applied pressure, 
 a pressure sensor array disposed on the sensing surface, wherein a measurement of the plurality of pressure sensors corresponds to an image, and 
 an image detector, receiving images from the pressure sensor array, generating cursor manipulation corresponding to changes between the images, wherein a sampling resolution of the sensing surface is based on at least one of periodically sampling alternating pixels in the pressure sensor array such that sampled pixels are distributed in a periodic pattern throughout the pressure sensor array and monitoring at least one of a plurality of zones in the pressure sensor array, wherein the plurality of zones are distributed in a non-overlapping pattern throughout the pressure sensor array, and wherein each of the plurality of zones includes multiple pixels of the pressure sensor array, the plurality of zones collectively providing navigation data. 
 
 
     
     
       2. The device, as defined in  claim 1 , wherein the cursor manipulation corresponds to planar directional movement. 
     
     
       3. The device, as defined in  claim 1 , wherein the cursor manipulation corresponds to data entry. 
     
     
       4. The device, as defined in  claim 1 , the image detector including:
 a controller; 
 a multiplex driver, transceiving data to and from the controller; 
 an image array, receiving data from the multiplex driver; 
 sense amplifiers, connected to the image array, transceiving data to and from the controller; 
 a serial port transceiving data with the controller; 
 current read access memory (RAM) connected to the sense amplifiers; 
 reference RAM, connected to the current RAM; 
 a predictor; 
 a cross-correlator receiving and processing data from the current RAM, reference RAM and the predictor; and 
 an interpolator, receiving data from the cross-correlator, transmitting data to the predictor and the controller. 
 
     
     
       5. The device, as defined in  claim 1 , wherein the mobile embedded device is selected from a group comprising personal data assistants and cellular phones. 
     
     
       6. A device, as defined in  claim 1 , wherein the sampling resolution of the sensing surface is based on the monitoring the multiple zones of the plurality of zones in the pressure sensor array. 
     
     
       7. A device, as defined in  claim 1 , wherein the sampling resolution of the sensing surface is based on the periodically sampling the alternating pixels in the pressure sensor array such that the sampled pixels are distributed in the periodic pattern throughout the pressure sensor array. 
     
     
       8. A system for providing cursor manipulation when using a human finger comprising:
 a sensing surface operative to sense contact by the human finger, the contact corresponding to applied pressure, the sensing surface having a sampling resolution based on at least one of periodically sampling alternating pixels in an array such that sampled pixels are distributed in a periodic pattern throughout the array and monitoring at least one of a plurality of zones in the pressure sensor array, wherein the plurality of zones are distributed in a non-overlapping pattern throughout the pressure sensor array, and wherein each of the plurality of zones includes multiple pixels of the pressure sensor array, the plurality of zones collectively providing navigation data; 
 a pressure sensor array disposed on the sensing surface, wherein a measurement of the plurality of pressure sensors corresponds to an image; and 
 an image detector, receiving images from the pressure sensor array, generating cursor manipulation corresponding to changes between the images. 
 
     
     
       9. The system, as defined in  claim 8 , wherein the cursor manipulation corresponds to planar directional movement. 
     
     
       10. The system, as defined in  claim 8 , wherein the cursor manipulation corresponds to data input. 
     
     
       11. The system, as defined in  claim 8 , the image detector including:
 a controller; 
 a multiplex driver, transceiving data to and from the controller; 
 an image array, receiving data from the multiplex driver; 
 
       sense amplifiers, connected to the image array, transceiving data to and from the controller;
 a serial port transceiving data with the controller; 
 current read access memory (RAM) connected to the sense amplifiers; 
 reference RAM, connected to the current RAM; 
 a predictor; 
 a cross-correlator receiving data from the current RAM, reference RAM, and the predictor; and 
 an interpolator, receiving data from the cross-correlator, transmitting data to the predictor and the controller. 
 
     
     
       12. A system, as defined in  claim 8 , wherein the sampling resolution is based on the monitoring the multiple zones of the plurality of zones in the pressure sensor array. 
     
     
       13. A system, as defined in  claim 8 , wherein the sampling resolution is based on the periodically sampling the alternating pixels in the pressure sensor array such that the sampled pixels are distributed in the periodic pattern throughout the pressure sensor array. 
     
     
       14. A method for finger navigation of a cursor comprising:
 sampling a portion of an array of pressure sensors to generate a first sample based on at least one of periodically sampling alternating pixels in the array such that sampled pixels are distributed in a periodic pattern throughout the array and monitoring at least one of a plurality of zones in the array, wherein the plurality of zones are distributed in a non-overlapping pattern throughout the array, and wherein each of the plurality of zones includes multiple pixels of the array, the plurality of zones collectively providing navigation data; 
 re-sampling the portion of the array to generate a second sample; and 
 comparing the first and second samples to determine planar movement of the finger to generate directional input reflected in navigational movement of the cursor. 
 
     
     
       15. A method, as defined in  claim 14 , wherein the portion is a subset of the array. 
     
     
       16. A method, as defined in  claim 15 , wherein the subset is a region of pressure sensors. 
     
     
       17. A method, as defined in  claim 16 , wherein the region has an area comparable to a fingerprint. 
     
     
       18. A method, as defined in  claim 16 , wherein the subset further comprises a second region of pressure sensors. 
     
     
       19. A method, as defined in  claim 14 , wherein the sampling includes sampling the portion of the array of pressure sensors to generate the first sample based on the monitoring the multiple zones of the plurality of zones in the array. 
     
     
       20. A method, as defined in  claim 14 , wherein the sampling includes sampling the portion of the array of pressure sensors to generate the first sample based on the periodically sampling the alternating pixels in the array such that the sampled pixels are distributed in the periodic pattern throughout the array.